Optically active mono-phosphate compounds have recently attracted attention as optically active Brønsted acid catalysts to catalyze asymmetric reactions represented by asymmetric Mannich reaction.
For example, Mannich reactions have been reported as one of the reactions using an optically active mono-phosphate compound as an asymmetric Brønsted acid catalyst (Patent Literature 1 and Non Patent Literature 1).
Patent Literature 1 describes a process for producing amines which includes reacting an imine compound with a nucleophilic compound in the presence of a mono-phosphate compound. In Non Patent Literature 1, N-tert-butoxycarbonyl-benzaldehyde imine and acetylacetone are reacted with each other using an optically active mono-phosphate as an asymmetric catalyst which has a bi-naphthyl skeleton as an optically active site, thus giving a β-aminoketone with a yield of 99% and an enantiomeric excess of 95% e.e. Further, Non Patent Literatures 2 and 3 describe optically active bis-phosphate compounds and asymmetric reactions using the compounds.